Health providers today need condensed and specific information from their patients in order to provide an improved treatment. In particular within areas where the muscle activity can shed a light on the status of the patient continuously monitoring is desirable. Such areas may for example be epilepsy, where patients can experience motor convulsions caused by excessive muscle activity. Furthermore, with increased focus on financial management of health care there is a need for monitoring patients at home and in heir everyday environment in order to effectively and properly diagnose and treat a patient.
Today patients or their caregivers observe and register seizures primarily by using a sheet whereon they have to fill in when they have had an epileptic seizure and preferably the duration. However, this can be very complicated as some times the patient will never notice a seizure as some seizures may be very subtle or in other situations the patient becomes unconscious and may wake up without knowing a seizure has occurred or do not know the duration or type of seizure. Thus, the data collected by the patients own input are usually very unreliable.
Moreover, apparatus and methods for monitoring patients and/or users in their daily environment need not only be reliable but also discreet and comfortable.
WO 95/15117 discloses monitoring of a motor activity signal which is separate from the monitoring of the brain activity signal. When the motor activity signal amplitude is within a predetermined motor window, a motor activity counter is incremented. When the motor activity signal amplitude is outside the predetermined motor window, the motor activity counter is decremented. An epileptic seizure is indicated when the motor activity counter value lies above a motor threshold.
However, many types of epileptic seizures exists and not all generate a heavy muscle activity but may instead generate subtle spasm where many different requirements has to be checked in order to determine that it is indeed an epileptic seizure. Thus, sophisticated monitoring devices are needed which beside occurrence of the motor convulsion also is capable of monitoring e.g. extent and/or the amplitude of the convulsion or other pan-peters which are relevant to epileptic seizures.
U.S. Pat. No. 6,440,067 discloses a method and system for remotely monitoring and identifying so-called Functional Activities by identifying specific signal patterns which correspond to a given Functional Activity.
In order to identify a signal pattern, in particular patterns from electromyographic signals, a high sampling rate as well as a significant time span is necessary. This requires a high level of processing which consequently requires a lot of power consumption. Thus, for use in devices where a low power consumption is preferred, i.e. due to size and/or battery lifetime, such a method would be inappropriate.
Moreover, while using a method for comparing signal patterns may be suitable in order to recognize controllable and repeatable activities such as walking, lifting etc., it is not suitable to use in order to detect epileptic seizures. An epileptic seizure is an uncontrollable action caused by abnormal electrical activity in the brain which generates signals that are individually different.